Assessing the Adequacy of Traditional Vertebral Landmarks as Upper Border of Whole Pelvic Radiotherapy Field for Stage IB2-IIB Cervical Cancer

Simple Summary Traditionally, the upper border of whole pelvic radiotherapy fields for cervical cancer was set using vertebral landmarks, potentially missing a part of the common iliac lymph node (CIN). This retrospective study investigated the impact of insufficient radiation coverage of CIN in stage IB2-IIB cervical cancer treatment. We compared outcomes between patients with full CIN coverage and those with partial coverage. Our results showed that patients with full CIN coverage had significantly better outcomes, including lower recurrence rates and higher survival rates. These findings suggest that using vascular anatomy (aortic bifurcation) as a guide for setting the upper border of radiation fields may be more effective than relying on vertebral landmarks. Our study highlights the importance of ensuring comprehensive coverage of the CIN area in cervical cancer treatment, which may influence future radiotherapy practices by encouraging the use of vascular landmarks for field border definition.Abstract This study investigates the impact of insufficient common iliac lymph node (CIN) irradiation on treatment outcomes in patients with stage IB2-IIB cervical cancer receiving concurrent chemoradiotherapy (CCRT). We retrospectively analyzed 68 patients with Federation of Gynecology and Obstetrics stage IB2-IIB, treated with weekly cisplatin-based CCRT from 2008 to 2018. Patients received external-beam whole pelvic radiotherapy (WPRT) and concurrent cisplatin chemotherapy, followed by high-dose-rate brachytherapy. The WPRT upper border was at L4-5 in 61 patients and L3-4 in 7 patients. Thirty-seven patients had the CIN area fully included (full-CIN group), while 31 had partial inclusion (partial-CIN group). Recurrence rates and survival outcomes were analyzed over a median follow-up of 111 months. Patient characteristics and the irradiated dose were comparable. Treatment failure occurred in three patients (8.1%) in the full-CIN group and in six patients (19.4%) in the partial-CIN group, with CIN and para-aortic lymph node recurrence in two and one patients, respectively. The 5-year cumulative recurrence rate was 0% for the full-CIN group and 11.4% for the partial-CIN group (p = 0.04). Cause-specific survival was 100% vs. 87.1% (p = 0.025), and the overall survival was 94.3% vs. 87.1% (p = 0.44). Fully including the CIN area in WPRT is crucial for stage IB2-IIB cervical cancer. Vascular anatomical margins should be considered over vertebral landmarks.